It is an understatement to say that the universe is vast.

Imagine that your car is a space ship, and you are driving to the sun with a galactically-imposed speed limit of 100 kilometers per hour (~62 miles per hour). At that rate, it would take you about 171 years to reach the sun.[1] Your great-grandchildren might actually get to see it up-close.

Now imagine that when you arrive at the sun, Chris, one of your great-grandchildren, decides that he wants to have a picnic on Pluto. So, he puts the car in gear and drives to the farthest planet from the sun. That trip takes 2625 years.

Should I even tell you how long it would take to drive from Pluto to the next nearest star? More than 46 million years. I hope that they improve fuel efficiency by then.

Light is the fastest moving thing, and its speed limit is enforced by the laws of the universe. That's pretty fast. As fast as light travels, it still takes light 4.3 years to reach us from the closest star.

Imagine that you could shrink the universe down so that the sun was the size of a dime[2], and place that dime at your feet while standing on the sidewalk in Washington, DC. Earth would hover about above your head about 7 feet off the ground (2.15m/7.05ft). On top of the nearby 34-story building, you might find Pluto (85m/282ft). If you walked to Proxima Centauri, our closest neighboring star, you would end up in Cleveland, Ohio (582km/362mi) and you could carry the Earth in your pocket the whole way because it would be smaller than a grain of sand.[3]

The next biggest astronomical body to measure could be the diameter of our galaxy. If you squished the Milky Way down to this 1 sun = 1 dime scale, you would still have to place 6 million normal-sized Earths end-to-end to reach all the way across.
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Imagine that our galaxy is just one of so many galaxies that we have yet to count them all and the vastness of space and our insignificant size starts to sink in. So when they say, "It's a small world," they're not kidding.